Over the last two decades, shape memory alloys (SMA) have attracted great interest as materials that could be beneficially employed in a wide variety of applications, including aerospace applications, naval applications, automotive applications, and medical applications. NiTi alloy is one of the more frequently used SMAs, due to its large flow stress and shape memory effect strain. Recently, porous NiTi has been considered for incorporation into medical implants, and as a high energy absorption structural material. While the properties of porous NiTi are intriguing, fabrication of porous NiTi is challenging. One prior art technique for fabricating porous NiTi is based on a combustion synthesis. However, studies have indicated porous NiTi synthesized by this method is brittle. Another fabrication method that has been investigated involves powder sintering; however, studies have indicated that porous NiTi fabricated using powder sintering is also brittle, and lacks a stress plateau in the stress-strain curve. A self-propagating high temperature synthesis (SHS) is a further technique that can be used to produce porous NiTi; yet again, the porous NiTi fabricated using SHS is undesirably brittle. Still another technique disclosed in the prior art employs a hot isostatic press (HIP), which also yields a brittle porous NiTi.
It would be desirable to provide techniques for fabricating porous NiTi that exhibits a higher ductility, i.e., which is not brittle. It would further be desirable to provide a new energy absorbing structure based on the properties of porous SMA, such as NiTi.